Sub-RPE Optically empty structures in Polypoidal Choroidal Vasculopathy: a novel optical coherence tomography finding

Abstract

Purpose: To describe the appearance of a novel OCT feature in PCV and report its prevalence in a clinical cohort Methods: We retrospectively analysed the OCT and ICGA images of eyes with PCV. Main outcome measures included the appearance, prevalence and longitudinal changes of ‘optically empty sub-RPE structures’ on OCT and correlate them with ICGA and OCTA. Results: We evaluated OCT of 55 patients. Each patient had monthly OCT from baseline to month 12. Presence of sub-RPE optically empty structures at any visit was detected in 10 eyes (7 at baseline, 3 during follow-up). These lesions are located under the RPE and are characterized by homogenously hyporeflective content similar to the vitreous cavity, which appear optically empty. Additional features include hypertransmission tail into choroid, round/ polygonal in shape surrounded by thin wall and fuzzy overlying RPE. When compared with ICGA, these structures can be colocalized to area of pooling associated with polypoidal lesions but can persist after polyp regression. No flow signal was detected within the center of these optically empty structures. Conclusion: Sub-RPE optically empty structures likely represent spaces not filled with blood and are distinct from the lumen of a polypoidal lesion.